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입자물리와 우주론
중성미자(렙톤(경입자)의 일종. 뉴트리노라고도 한다)와 우주론을 연구하고 있다. 중성미자는 역사적으로는 붕괴 때에 에너지보존법칙을 설명하기 위해 도입되었고, 현대 과학에서 중성미자는 우주론적으로 매우 중요시되고 있는데, 중성미자를 검출해 우주를 관측하려는 중성미자망원경도 발명되었다. 중성미자망원경은 별의 표면에서 나온 빛과 전파를 탐지하는 광학망원경이나 전파망원경과는 달리 별 속 깊숙이서 핵융합반응을 일으켜 방출되는 중성미자를 검출함으로써 별의 내부 정보를 알아내려는 것이다. 중요한 것은 중성미자망원경으로 우주탄생 1초 후에 발생한 중성미자를 검출할 수 있으리라는 기대이다. 중성미자망원경이 개량되면 언젠가 태초의 영상을 볼 수 있을 것이라는 생각에서 중성미자천문학은 앞으로도 계속 각광을 받을 것이라 기대된다.
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Heavy majorana neutrinos at e(+)e(-) colliders Title : Heavy majorana neutrinos at e(+)e(-) colliders Journal : PHYSICAL REVIEW LETTERS, 1999
논문 NUMBER P98050 AUTHOR Kim, CW TITLE Heavy majorana neutrinos at e(+)e(-) colliders ARCHIVE FILE JOURNAL PHYSICAL REVIEW LETTERS, 1999 ABSTRACT We investigate possibilities for detecting heavy Majorana neutrinos (Ns) in e(+)e(-) at LEP200 and future linear colliders. We concentrate on the processes where the pairs of intermediate heavy Ns produce a clear signal of total lepton number violation (e(+)e(-) --> NN --> W(+)l(-)W(+)l(-).). Such a signal is not possible if the heavy neutrinos are of Dirac nature. Our approach is general in the sense that the intermediate Ns can be either on shell or off shell. Discussion of the relative numerical importance of the s and the t + u channels of the NN production is also included.
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Supersymmetric neutrino masses and mixing with R-parity violation Title : Supersymmetric neutrino masses and mixing with R-parity violation Journal : NUCLEAR PHYSICS B, 1999
논문 NUMBER P98014 AUTHOR Kim, CW,Chun, EJ,Kang, SK TITLE Supersymmetric neutrino masses and mixing with R-parity violation ARCHIVE hep-ph/9807327 FILE JOURNAL NUCLEAR PHYSICS B, 1999 ABSTRACT In the context of the minimal supersymmetric standard model, non-zero neutrino masses and mixing can be generated through renormalizable lepton number (and thus R-parity) violating operators. It is examined whether neutrino mass matrices from tree and one-loop contributions can account for two mass-squared differences and mixing angles that explain current experimental data. By accommodating, in particular, the solar and atmospheric neutrino data, we find interesting restrictions not only on the free parameters of the theory, such as lepton number violating couplings and soft parameters, but also on the oscillation parameters of atmospheric neutrinos. (C) 1999 Elsevier Science B.V.
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Gravitational effects on the neutrino oscillation in vacuum Title : Gravitational effects on the neutrino oscillation in vacuum Journal : NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS, 1999
논문 NUMBER AUTHOR Kim, CW TITLE Gravitational effects on the neutrino oscillation in vacuum ARCHIVE FILE JOURNAL NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS, 1999 ABSTRACT The propagation of neutrinos in a gravitational field is studied by developing a method of calculating a covariant quantum-mechanical phase in a curved space-time. The result is applied to neutrino propagation in the Schwarzschild metric.
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Comment on the possible electron neutrino excess in the Super-Kamiokande atmospheric neutrino experiment Title : Comment on the possible electron neutrino excess in the Super-Kamiokande atmospheric neutrino experiment Journal : PHYSICS LETTERS B, 1998
논문 NUMBER P98022 AUTHOR Kim, CW TITLE Comment on the possible electron neutrino excess in the Super-Kamiokande atmospheric neutrino experiment ARCHIVE FILE JOURNAL PHYSICS LETTERS B, 1998 ABSTRACT We investigate the implications of a possible excess of the electron neutrino events in the Super-Kamiokande atmospheric neutrino experiment. The excess, if real, leads to constraints on the v(mu)<----> v(e), v(mu)<----> v(tau) and v(c)<----> v(tau) oscillation parameters. Specifically, the excess implies that v,- y, and I; - vi mixings are large whereas v,- 1 mixing Is small. We show that the electron neutrino excess favors the large mixing angle MSW solution of the solar neutrino problem. (C) 1998 Elsevier Science B.V. All rights reserved.
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Three neutrino Delta m(2) scales and the singular seesaw mechanism Title : Three neutrino Delta m(2) scales and the singular seesaw mechanism Journal : PHYSICAL REVIEW D, 1998
논문 NUMBER P98001 AUTHOR Kim, CW,Chun, EJ TITLE Three neutrino Delta m(2) scales and the singular seesaw mechanism ARCHIVE hep-ph/9802209 FILE JOURNAL PHYSICAL REVIEW D, 1998 ABSTRACT It is shown that the singular seesaw mechanism can simultaneously explain all the existing data supporting nonzero neutrino masses and mixing. The three mass-squared differences that are needed to accommodate the atmospheric neutrino data (through nu(mu) - nu(s) oscillation), the solar neutrino data via the MSW mechanism (through nu(e) - v(tau) oscillation), and the positive result of nu(mu) - nu(e) oscillation from the LSND can be generated by this mechanism, whereas the vacuum oscillation solution to the solar neutrino problem is disfavored. We find that the electron and tau neutrino masses are of the order of 10(-3) eV, and the muon neutrino and a sterile neutrino an almost maximally mixed to give a mass of the order of 1 eV. Two heavy sterile neutrinos have a mass of the order of 1 keV which can be obtained by the double seesaw mechanism with an intermediate mass scale similar to 10(5) GeV. A possible origin of such a scale is discussed. [S0556-2821(98)04917-0].
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Neutrino self-energy and dispersion in a medium with a magnetic field Title : Neutrino self-energy and dispersion in a medium with a magnetic field Journal : PHYSICAL REVIEW D, 1998
논문 NUMBER P98006 AUTHOR Kim, CW TITLE Neutrino self-energy and dispersion in a medium with a magnetic field ARCHIVE FILE JOURNAL PHYSICAL REVIEW D, 1998 ABSTRACT We calculate the one-loop thermal self-energy of a neutrino in a constant and homogeneous magnetic field to all orders in the magnetic field strength using Schwingers proper time method. We obtain the dispersion relation under various conditions. [S0556-2821(98)08618-4].
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Coherence of neutrino oscillations in the wave packet approach Title : Coherence of neutrino oscillations in the wave packet approach Journal : PHYSICAL REVIEW D, 1998
논문 NUMBER P97007 AUTHOR Kim, CW TITLE Coherence of neutrino oscillations in the wave packet approach ARCHIVE hep-ph/9711363 FILE JOURNAL PHYSICAL REVIEW D, 1998 ABSTRACT The temporal and spatial coherence widths of the microscopic process by which a neutrino is detected are incorporated in the quantum mechanical wave packet treatment of neutrino oscillations, confirming the observation of Kiers, Nussinov, and Weiss that an accurate measurement of the neutrino energy in the detection process can increase the coherence length. However, the wave packet treatment presented here shows that the coherence length has an upper bound, determined by the neutrino energy and the mass-squared difference, beyond which the coherence of the oscillation process is lost. [S0556-2821(98)01415-5].
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Atmospheric neutrino oscillations with three neutrinos and a mass hierarchy Title : Atmospheric neutrino oscillations with three neutrinos and a mass hierarchy Journal : NUCLEAR PHYSICS B, 1998
논문 NUMBER P97004 AUTHOR Kim, CW TITLE Atmospheric neutrino oscillations with three neutrinos and a mass hierarchy ARCHIVE FILE JOURNAL NUCLEAR PHYSICS B, 1998 ABSTRACT A comprehensive formalism for the description of neutrino oscillations in the Earth in a general scheme with three massive neutrinos and the mass hierarchy m(1) much less than m(2) much less than m(3) is presented. Using this formalism, which is valid both in vacuum and in a medium, the matter effect on the oscillations of low-energy neutrinos is discussed, pointing out the existence of very long oscillations which are independent of the neutrino masses and the neutrino energy, and are very sensitive to the matter density along the neutrino trajectory. As an example of application of the formulation, a fit of the Kamiokande atmospheric neutrino data with the matter effect taken into account for neutrinos propagating in the Earth is presented. The results of the fit indicate that 4 x 10(-3) eV(2) less than or similar to m(3)(2) less than or similar to 4 x 10(-2) eV(2) and the oscillation amplitudes in all channels (v(u) reversible arrow v(e), v(u) reversible arrow v(tau), v(e) reversible arrow v(tau)) could be large. Hence, long-baseline experiments with reactor (CHOOZ and Pale Verde) and accelerator (K2K, MINOS and ICARUS) neutrinos could observe neutrino oscillations in all channels with a relatively large statistics. (C) 1998 Elsevier Science B.V.
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When do neutrinos cease to oscillate? Title : When do neutrinos cease to oscillate? Journal : PHYSICS LETTERS B, 1998
논문 NUMBER P97003 AUTHOR Kim, CW TITLE When do neutrinos cease to oscillate? ARCHIVE FILE JOURNAL PHYSICS LETTERS B, 1998 ABSTRACT In order to investigate when neutrinos cease to oscillate in the framework of quantum field theory, we have reexamined the wave packet treatment of neutrino oscillations by taking different sizes of the wave packets of the particles involved in the production and detection processes. The treatment is shown to be considerably simplified by using the Grimus-Stockinger theorem which enables us to carry out the integration over the momentum of the propagating neutrino. Our new results confirm the recent observation by Kiers, Nussinov and Weiss that a precise measurement of the energies of the particles involved in the detection process would increase the coherence length. We also present a precise definition of the coherence length beyond which neutrinos cease to oscillate. (C) 1998 Elsevier Science B.V.
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Pulsar velocity with three-neutrino oscillations in non-adiabatic processes Title : Pulsar velocity with three-neutrino oscillations in non-adiabatic processes Journal : PHYSICS LETTERS B, 1998
논문 NUMBER P97006 AUTHOR Song, J,Kim, CW TITLE Pulsar velocity with three-neutrino oscillations in non-adiabatic processes ARCHIVE FILE JOURNAL PHYSICS LETTERS B, 1998 ABSTRACT We have studied the position dependence of neutrino energy on the Kusenko-Segre mechanism as an explanation of the proper motion of pulsars. The mechanism is also examined in three-generation mixing of neutrinos and in a non-adiabatic case. The position dependence of neutrino energy requires the higher value of magnetic field such as B similar to 3 x 10(15) Gauss in order to explain the observed proper motion of pulsars. It is shown that possible non-adiabatic processes decrease the neutrino momentum asymmetry, whereas an excess of electron neutrino flux over other flavor neutrino fluxes increases the neutrino momentum asymmetry. It is also shown that a general treatment with all three neutrinos does not modify the result of the two generation treatment if the standard neutrino mass hierarchy is assumed. (C) 1998 Elsevier Science B.V.
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Finite temperature effects on the neutrino decoupling in the early Universe Title : Finite temperature effects on the neutrino decoupling in the early Universe Journal : PHYSICAL REVIEW D, 1997
논문 NUMBER P97002 AUTHOR Kim, CW TITLE Finite temperature effects on the neutrino decoupling in the early Universe ARCHIVE FILE JOURNAL PHYSICAL REVIEW D, 1997 ABSTRACT Leading finite temperature effects on the neutrino decoupling temperature in the early Universe have been studied. We have incorporated modifications of the dispersion relation and the phase space distribution due to the presence of particles in the heat bath at a temperature of around 1 MeV. Since both the expansion rate of the Universe and the interaction rate of a neutrino are reduced by finite temperature effects, it is necessary to calculate thermal corrections as precisely as possible in order to find the net effect on the neutrino decoupling temperature. We have performed such a calculation by using finite temperature field theory. It has been shown that the finite temperature effects increase the neutrino decoupling temperature by 4.4%, the largest contribution coming from the modification of the phase space due to the thermal bath.
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Magnetic properties of neutrinos in high temperature SU(2)(L)circle times U(1) gauge theory Title : Magnetic properties of neutrinos in high temperature SU(2)(L)circle times U(1) gauge theory Journal : PHYSICS LETTERS B, 1997
논문 NUMBER P97001 AUTHOR Kim, CW TITLE Magnetic properties of neutrinos in high temperature SU(2)(L)circle times U(1) gauge theory ARCHIVE FILE JOURNAL PHYSICS LETTERS B, 1997 ABSTRACT We calculate the finite temperature self-energy for neutrinos in the presence of a constant magnetic field in a medium in the unbroken SU(2) x U(1) model, We obtain the exact dispersion relation for such neutrinos and find that the thermal effective mass is modified by the magnetic field, We also find a simple analytic expression for the dispersion relation and obtain the index of refraction for large neutrino momentum. (C) 1997 Elsevier Science B.V.
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- Professor Emeritus, Korea Institute for Advanced Study, Seoul, Korea
- Professor Emeritus, Johns Hopkins University, Baltimore, MD
- 1997-2004 President, Korea Institute for Advanced Study
- 1998-2001 Vice President (in charge of Academic Affairs),Korea Academy of Science and Technology
- 1987-1990 Director of Graduate Program(JHU)
- 1990-1993 Vice Chair, Dept. of Physics & Astronomy(JHU)
- 1973-2002 Professor(JHU)
- 1969-73 Associate Professor(JHU)
- 1966-69 Assistant Professor(The Johns Hopkins University)
- 1963-66 Research Associate, University of Pennsylvania
- 1963 Ph.D. Indiana University
- 1959 -1960 M.S. University of Notre Dame
- 1958 B.S Seoul National University
- Chong- Am Science Prize (Korea Academy of Science and Technology)
- Korean National Decoration, Moran Order of Merit
- Fellow, Korean Physical Society
- Fellow, American Physical Society
- Fellow, Korean Academy of Sciences and Technology
- University Fellowship at Indiana University
- Syng Man Rhee Award at Graduation, SNU
- Syng Man Rhee (President of Korea) Scholarship
- Office:1213 / TEL) 82-2-958-3871 / FAX) 82-2-958-3770
- School of School of Physics, Korea Institute for Advanced Study
서울특별시 동대문구 회기로 85(서울특별시 동대문구 청량리동 207-43) 우:130-722
